I was just thinking of Hiphop and XHP, and they both seem like a huge amount of work and I've heard about improvements to the interpreter to optimize it for the

I was just thinking of Hiphop and XHP, and they both seem like a huge amount of work and I've heard about improvements to the interpreter to optimize it for their servers... of course it might all be FUD for competitors, they might actually have everything coded in Common Lisp behind the scenes ;)